reveaLInG the past throUGh dna

argued in a May, 2011 letter to the journal Science, should not favor “the ideology of a local American Indian group over the legitimacy of science.”

Not long ago, such stormy rhetoric typified the relationships between scientists and Native Americans in the U.S. and Canada. Tired of being treated as faceless, powerless subjects by non-native researchers, many tribes began pushing back in the 1970s. They imposed new rules on researchers and demanded the return of ancient remains and artifacts that had been hauled off to universities and museums. Some tribes even went to court to block scientists from studying newly discovered skeletons—the best-known example being Kennewick Man—or to challenge projects they believed

had skirted ethical standards. Mistrust of geneticists seeking Native Americans’ DNA for biomedical or anthropological studies was particularly acute. According to a 2008 study in the American Journal of Public Health, Alaskan Natives have a saying: “Researchers are like mosquitoes. They suck your blood and leave.” But that mistrust is giving way to greater cooperation between DNA researchers and members of indigenous groups. “The culture of science has changed,” said Dennis O’Rourke, a genetic anthropologist at the University of Utah in Salt Lake City who has been involved in studies of Native American DNA since the 1980s. “There is greater collaboration with Native American communities, and more awareness of their perspectives and needs.” Native people “aren’t anti-science and are often very interested in the same questions that researchers are asking,” said Kim TallBear, a member of South Dakota’s Sisseton-Wahpeton Oyate tribe and an anthropologist at the University of California, Berkeley, who studies the impact of anthropological genetics on indigenous groups. “But they are increasingly aware of the ethical and cultural implications of genetic research, and rightly concerned about how this material is used, who benefits, and who has a say in the questions that are asked.” One result, observers said, is that despite a thicket of difficult ethical and legal issues, alliances between A researcher works at On Your Knees Cave in Alaska, where the remains of an approximately DNA researchers and Native Ameri10,000-year-old individual were discovered. Geneticists extracted DNA from the remains. can groups are now producing a steady stream of new and important genetic insights into the history of humans in the Americas. By analyzing DNA from living people and ancient DNA from human remains, researchers have identified at least 15 genetically-distinct founding lineages, for instance, and begun to trace the timing and routes of early migrations. And new technologies, including the ability to inexpensively sequence a person’s whole genome, could extract even more information from the hereditary molecule. “It’s an exciting time,” said geneticist Ripan Malhi of the University of Illinois, Urbana-Champaign. “We’re starting to see just the tip of the iceberg of what DNA can tell us about those initial migrants from Asia and the early movement of populations across the Americas.”

The new findings mark the latest chapter in a long and sometimes painful history of contacts between geneticists and indigenous groups. A number of “unfortunate interactions” have often left tribes “with a sense of mistrust, stigmatization, or weakened political integrity,” Roderick McInnes, a geneticist at McGill University in Montreal, Canada, told the annual meeting of the American Society of Human Genetics in 2010. One case, he noted, dates to the early 1980s, when Canadian biomedical researchers collected DNA samples from the Nuu-chah-nulth tribe of British Columbia for a study of arthritis. Tribal members gave their consent for that study, but they weren’t asked or told when researchers later used the DNA for other studies, including an analysis of the tribe’s genetic ancestry, and links to other past and present populations. Tribal leaders objected, and ultimately won the return of the samples 20 years after they were first collected. “The perception of researchers that DNA collected for research becomes their property is actually a common problem,” McInnes noted. Indeed, the Nuuchah-nulth’s experience helped prompt Canada to develop new guidelines for health research involving natives, which call for scientists to consider the samples they collect as being “on loan.” The guidelines also encourage researchers to “understand and respect Aboriginal world views” and “a community’s jurisdiction over the conduct of the research.” A similar, but more recent, case involved the Havasupai tribe of Arizona. The tribe discovered that DNA collected from its members for a diabetes study at Arizona State University had also been used for ancestry research and other studies, including one that concluded that the small group had a high rate of inbreeding. “The tribe felt stigmatized,” said McInnes, “by studies [it] had not authorized.” Researchers said tribal members had provided informed consent for the wider studies, but in 2010 the university reached a $700,000 settlement with the Havasupai, which included a commitment to return the samples. The case, McInnes said, “makes instructive reading for any geneticist who plans to conduct research with indigenous populations. All of the outcomes were bad.”

It’s understandable why many Native people are skeptical of such research, said TallBear. “Science says it is about modernity and reality,” she notes. But so did “Christian missionaries and people who wanted to ‘civilize’ native people in the 19th century. So there is some sense that this is part and parcel of that historic colonization project.” Genetic research also has the potential to threaten or undermine a tribe’s “own origin story and cultural narrative,” she notes. And it can raise questions about “who is and is not an ‘authentic’ Indian… even though genetic identity is not necessarily cultural identity.” Too often, she said, scientists and journalists “confuse the concept of a genetically-similar population with the idea of a cultural group that shares a language or other cultural identifiers… ancestry is about a lot more than just DNA.”

First Nations’ members participate in a food burning ceremony for the dead immediately following the excavation of 5,000-year-old human remains at Big Bar Lake in British Columbia. The High Bar and Canoe Creek First Nations allowed the remains to be tested for DNA.

Many of those concerns were very much in the air a decade ago, when Malhi first began trying to work with First Nations bands in Canada. “There was a lot of tension,” he recalled. “When I went out to communities to talk about collaboration, I would hear things like: ‘Why should I trust you?’” Malhi said he ultimately won the trust of some tribes—but not all—by being “transparent” about what he wanted to do, “and making sure I listened to their concerns.” It was critical that tribe members were “not just subjects but participants in the research who had input.” winter • 2011-12

These days, Malhi has collaborations with a number of tribes, and others have approached him to discuss possible joint studies. But “before I even mention collecting DNA samples, I give a talk to the community in general about what we can and can’t do with this information,” he said. And once a research project is begun, “it’s a multi-year process. I go back every year to report on the most recent results, talk with the community to explain the genetic patterns we are seeing, and meet with individual participants to answer any questions they have.” Tribal members have also appeared as co-authors on scientific presentations, such as an analysis Malhi’s team conducted with Canada’s Canoe Creek Band of ancient DNA from two 5,000-year-old skeletons found near China Lake, British Columbia in 1982. The tribe agreed to the testing before reburying the remains in 2006.

Other researchers and Native groups have adopted similar practices in forging productive relationships, but “there isn’t one single way to do it,” said O’Rourke. “There’s no magic formula, you just have to get in there and work directly with people,” agreed Jerome Cybulski of the Canadian Museum of Civilization in Ottawa, who collaborates with Malhi and played a central role in the study of the China Lake remains. And many emphasize that native groups—there are 565 recognized tribes in the U.S. and more than 600 First Nations bands in Canada—can have very different perspectives on proposed research. While some communities are reluctant to allow analyses of skeletons, for example, others “can have this sense that the ancestors were revealed in order for the living to learn more about them,” said Malhi. Those same communities, however, may be uncomfortable with the idea of collecting DNA from living people, he added.

The complexity of such negotiations, however, hasn’t prevented gene researchers from gaining an increasingly nuanced picture of what has been called “the last migration.” North and South America “were the last large uninhabited landmasses that ice age humans settled,” anthropologists Jeffrey Long of the University of New Mexico in Albuquerque and Maria Cátria Bortolini of the Federal University of Rio Grande do Sul in Brazil noted in a September, 2011 special issue of the American Journal of Physical Anthropology (AJPA) devoted to new DNA findings on the genetic diversity of Native Americans. As early as the 1800s, scientists studying physical traits had hypothesized that Native Americans were the descendants of people from Asia, ultimately proposing that the migrants had moved across a land bridge that once connected modern day Siberia to Alaska. By the 1960s, geneticists were examining diversity relative to recent patterns of population size and gene flow resulting from migration, but such studies really took off in the 1980s with the introduction of powerful new technologies for extracting and sequencing various types of DNA.

Although most of a cell’s DNA is found in the nucleus, Long and Bortolini stated the first major finding came from the relatively small ring of DNA found in human mitochondria, energy-making organelles that are often called the cell’s power plants. Mitochondrial DNA (mtDNA), which is inherited only from the mother, is useful for examining the relatedness of different populations. In the early 1990s, researchers discovered that mtDNA from most Native Americans fell into four major ancestral lineages known as A, B, C, and D. These so called haplogroups are also common in populations in Mongolia, Tibet, and Siberia, and “this distribution suggests that Northern Asian populations are most closely related to Native Americans,” Long and Bortolini wrote.

Later studies of DNA from the cell’s Y chromosome, which is found only in men, arrived at the same conclusion. And over the last decade or so, wider sampling and more sophisticated technologies have allowed researchers to identify several less common haplogroups—including X and M—and numerous subpopulations within the original four. All told, there are now at least 15 recognized founding lineages, and that number is expected to keep growing as more DNA is analyzed. But the new discoveries haven’t altered the basic Asia-to-America theory, and, according to Long, “the genetic data are consistent with a single migration of people into the Americas.”

Exactly when and how these migrants moved to the Americas, however, has been the subject of much scientific debate. The genetic, archaeological, and linguistic data suggest that there was a major influx of migrants into northwestern North America between roughly 15,000 and 18,000 years ago. But over the last decade, evidence has grown that the migrants didn’t come directly from Asia. Some researchers suspect that about 30,000 years ago a founder population first moved from Asia to Beringia (the land that once connected Siberia and Alaska). Then there was a pause in the migration—possibly for as long as 15,000 years. That would have been long enough for the ancient Beringians to become cut off from their Asian forebearers and develop very different genetic profiles. Then, the Beringians carried those genes into North America. Although many questions still remain, this “Beringia standstill” or “Beringian incubation” hypothesis has gained support from the newest genetic analyses, including a review of more than 60 studies of ancient DNA samples that O’Rourke and his colleagues published in the AJPA special issue. “It appears there was some kind of isolation—whether in Beringia or some Asian backwater,” O’Rourke said.

DNA evidence also supports the view that once the migrants arrived, they spread south. Native populations in the northern regions tend to have higher genetic diversity than those in the south; that gradient is what geneticists would expect to see as groups moved farther from their founding population’s point of origin.

Other studies suggest they may have favored a coastal route, at least initially. That idea is supported by evidence that the living members of tribes along the West coast of North and South America share genetic markers found in ancient DNA extracted from skeletons discovered in Alaska and the Pacific Northwest. One study revealed that living members of California’s Chumash tribe shared genetic markers with

Ripan Malhi discusses the uses and limitations of DNA research with members of the Lax Kw’alaams First Nation.

ancient DNA taken from an approximately 10,000-year-old human tooth recovered from Alaska’s On Your Knees Cave. Such data “don’t rule out the idea that early people migrated along some inland corridors,” said Malhi, “but the coastal hypothesis does seem to be gaining popularity.”

Genetic data is also allowing researchers to test some provocative ideas about the relationship between the spread of cultures and continental geography. Years ago, biologist and noted author Jared Diamond of the University of California, Los Angeles, suggested that domesticated plants and animals—whether transported by migrants or trade between peoples—are likely to move more quickly along east-west lines of latitude than along north-south lines of longitude. That’s because climate and environmental conditions are more similar along latitude lines, while they can change dramatically along lines of longitude. That suggests the movement of people, technologies, and culture in the Americas, much of which was north to south, should have been slower than such movements in Eurasia, which tended to be east to west. To test that prediction, Sohini Ramachandran of Brown University in Providence, Rhode Island and Noah Rosenberg of Stanford, compared the genetic variation found in 29 Native American populations to the variation in 39 Eurasian indigenous groups. Confirming Diamond’s theory, they found more variation in the Native American groups, they reported in the AJPA special issue, suggesting greater isolation of populations and “a reduced speed for gene flow in the Americas since its initial peopling.” That lower level of interaction between early groups “may partly explain the relatively slower diffusion of crops and technologies through the Americas,” compared to Eurasia, they wrote. Such studies “can really help us reconsider how we think about colonization” as well as “raise new questions,” O’Rourke said.

Those questions are likely to keep piling up, Malhi said, with the advent of new and cheaper genetic technologies and wider sampling of DNA from indigenous groups. “We’re going to be seeing a lot more detail,” he predicted. So far, for instance, researchers haven’t been able to extract the ancient DNA needed to sequence the full nuclear genome of an early migrant; that is one reason researchers are so interested in the La Jolla skeletons, which were exceptionally well-preserved. But achieving that goal will take more than just technical advancements; it will require researchers and Native people to agree on what is acceptable.

Malhi believes that one way to reach that agreement is to have more Native people trained in genetics. “Training Native Americans to do this science would produce all kinds of benefits, to both their communities and the scientific community,” he said. To that end, last year he organized the first Summer Internships for Native Americans in Genomics (SING), which brought about a dozen students to Illinois for hands-on workshops and discussions of cultural and ethical issues. “It’s a start,” he said, “to doing better science by bringing a different cultural perspective to our work.”

DAVID MALAKOFF is a science writing living in Alexandria, Virginia. His article “The Mesoamerican-Southwest Connection” appeared in the Fall 2011 issue of American Archaeology.